Investigation of the Energy-Transfer Mechanism in Ho3+- and Yb3+-Codoped Lu2O3 Phosphor with Efficient Near-Infrared Downconversion
Investigation of the Energy-Transfer Mechanism in Ho3+- and Yb3+-Codoped Lu2O3 Phosphor with Efficient Near-Infrared Downconversion
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Ho3 和 Yb3 共掺杂 Lu2O3 荧光粉高效近红外下转换能量传递机制的研究
DOI：
10.1021/acs.inorgchem.6b02600
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发表时间：
2017
影响因子：
4.6
通讯作者：
Zhang Jiahua
中科院分区：
文献类型：
--
作者：
Xiang Guotao;Ma Yan;Zhou Xianju;Jiang Sha;Li Li;Luo Xiaobing;Hao Zhendong;Zhang Xia;Pan Guo-Hui;Luo Yongshi;Zhang Jiahua
采用高温固相法合成了Ho 3+和Yb 3+共掺杂的立方相Lu 2 O3粉体。用X射线衍射仪对粉体的晶体结构进行了表征。通过稳态光谱（包括可见光和近红外光谱）证实了Ho 3+离子和Yb 3+离子之间的能量转移（ET）现象。除此之外，还测量了衰变曲线以证实ET过程的存在。当激发波长为446 nm时，样品出现了下转换现象，对应于Ho 3+：5I 8 → 5G 6/5 F1的跃迁。通过分析Ho ~（3+）：5 F3能级的初始转移速率与Yb ~（3+）掺杂浓度的关系，指出Ho ~（3+）离子的5 F3态到Yb ~（3+）离子的2F 5/2态的电子转移主要是通过两步电子转移过程，而不是人们长期认为的协同电子转移过程。此外，在Lu_2O_3：1%Ho_3 +/30%Yb_3+体系中，电子转移效率可达62%。与其中NIR光子全部由受体Yb 3+发射的常见情况不同，敏化剂Ho 3+在446 nm波长激发时也对NIR发射作出贡献。同时，Ho 3+的5I 5 → 5I 8跃迁和5 F4/5S 2 → 5I 6跃迁以及Yb 3+的2F 5/2→ 2F 7/2跃迁与晶体硅太阳电池的最佳光谱响应相匹配。目前的研究表明，Lu 2 O3：Ho 3 +/Yb 3+是一种很有前途的提高晶体硅太阳电池转换效率的材料。
A high-temperature solid-state method was used to synthesize the Ho3+- and Yb3+-codoped cubic Lu2O3powders. The crystal structures of the as-prepared powders were characterized by X-ray diffraction. The energy-transfer (ET) phenomenon between Ho3+ions and Yb3+ions was verified by the steady-state spectra including visible and near-infrared (NIR) regions. Beyond that, the decay curves were also measured to certify the existence of the ET process. The downconversion phenomena appeared when the samples were excited by 446 nm wavelength corresponding to the transition of Ho3+:5I8→5G6/5F1. On the basis of the analysis of the relationship between the initial transfer rate of Ho3+:5F3level and the Yb3+doping concentration, it indicates that the ET from5F3state of Ho3+ions to2F5/2state of Yb3+ions is mainly through a two-step ET process, not the long-accepted cooperative ET process. In addition, a 62% ET efficiency can be achieved in Lu2O3: 1% Ho3+/30% Yb3+. Unlike the common situations in which the NIR photons are all emitted by the acceptors Yb3+, the sensitizers Ho3+also make contributions to the NIR emission upon 446 nm wavelength excitation. Meanwhile, the5I5→5I8transition and5F4/5S2→5I6transition of Ho3+as well as the2F5/2→2F7/2transition of Yb3+match well with the optimal spectral response of crystalline silicon solar cells. The current research indicates that Lu2O3: Ho3+/Yb3+is a promising material to improve conversion efficiency of crystalline silicon solar cell.